Last month my sister Emma gave me an unforgettably stylish party to celebrate my 50th birthday.

It was a glorious summer night and the bohemian Indian tent that nestled on the edge of a bluebell wood was decorated with fat, overblown pink peonies.

She'd hired Rhubarb to do the food and the Abba tribute band that performed after dinner was so joyously seductive it made even the über-inhibited dance until dawn.

At one point my husband, John, took to the stage with Will Young (both in satin capes) and they joined the band in a rousing rendition of Take A Chance On Me while the dance floor throbbed with guests aged from 18 to 80. It was one of the greatest nights of my life.

One detail that made the evening so special - apart from being surrounded by my closest friends - was the presence of Boothnation's Photobooth.

Photobooth is the star guest that just keeps on giving; the "don't-stop-till-you've-had-enough" ice-breaking, must-have, party drug of the Noughties.

The brainchild of still life and portrait photographer Seamus Ryan, Photobooth is a mobile photography studio which you can hire for the night.

A glamorous-looking version of the bog-standard railway station fixture, it operates on nearly the same principle.

At private parties, obviously, the cost is pre-paid, so there is no fumbling for the correct change, but you still go in, pull the curtain, pose, wait for the flash to go off and then step outside to collect your photographs.

One set is a souvenir for the guests to go home with, the other copy is stuck into a keepsake album.

The real genius behind this venture is the fact that all the photographs are spectacularly flattering. Everyone looks a better/younger/thinner version of themselves.

It's as if all the photos have been surreptitiously Photoshopped and airbrushed on their short journey from interior flash to outside collection.

Even celebrity guests who might baulk at having their photograph taken in "uncontrolled conditions" were thrilled at the outcome and merrily queued up again and again.

As did all of us - there is something irresistibly infantile and moreish about being given the opportunity to lark about with old mates and pull silly faces behind a cloth curtain.

"The great lighting is the currency," smiles Ryan. "Because that's how I made my reputation. Each travelling booth is technically equipped with five-star lighting and a lifetime of expertise. It's like studio-quality photos in a box."

His money-spinning brainchild was developed through chance and circumstance.

Every Sunday morning he would open his photography studio on Columbia Road to the public, inviting anyone passing by to come in and be photographed.

Every week he would dream up a different theme; some days he would photograph the contents of handbags, others he would focus on documenting the soles of people's shoes.

It was originally an exercise done just for fun until it proved such a popular Sunday event he decided to build a booth "around a lighting system" purely to amuse the long, snaking queue of people waiting outside his studio.

"Last year I was approached by the National Portrait Gallery and my booth was booked to document a Fashionista Friday event they were hosting and overnight the concept took off. It became like a runaway train," he says.

Since then, Photobooth has developed a cult following. Ryan never advertises and all bookings are generated purely by word of mouth.

Nigella Lawson hired it this year to provide post-turkey family entertainment on Christmas Day; it's appeared at Selfridges for Stella McCartney's latest launch, was the main attraction at the Mamma Mia! film premiere and wowed all the guests at Agyness Deyn's birthday party.

Following the success of my party, Louise Fennell booked the booth for her daughter Coco's 21st.

"It was the best birthday present," says Coco. "It's a great way to document a party; the downward spiral of drunkenness and high jinks forever captured."

My sister Emma reckons the real success of Photobooth is the way it places guests at ease.

"They get to choose who to be photographed with and how they want to look. It avoids those awful "posed party snaps" you're often left with at the end of the night."

She's right. Were my house to go up in flames I now know which object I'd rush to save: it would be my party album.

Where to get your party photobooth

Boothnation: packages from £1,545 with four hours' shoot time and any choice of booth theme. (020 7613 1560, www.boothnation.com)

Groovy Booth: four hours/£595, eight hours/£995, including leopard-skin booth option. (0800 612 0331, www.groovybooth.com)

Party Photobooth Hire: set package £450, including three hours' shoot time. (0844 3578926, www.party-photobooth-hire.co.uk)

Snappabox: from £500 for three hours, unlimited prints and DVD. Dress-up box also available. (0845 680 8995, www.snappabox.com)

The Photobooth Company: packages for retro booths from £650. Includes event attendant, full delivery and unlimited photos. (07970 141 633, www.thephotoboothcompany.co.uk).